This invention relates to centrifuge systems for the general processing of fluids and, more specifically, a centrifugal device for liquids, such as blood.
This invention deals with a centrifugal device for liquids, such as blood, containing suspended particles, comprising a mounted first drive that rotates, a mounted second drive unit that rotates, coaxially to the first drive unit, means to drive the first and the second drive units with a rotation ratio of 2/1 among each other, a centrifugal unit for said liquid, comprising at least three channels that link the center to a peripheral separation chamber, devices to make this centrifugal unit integral with the first drive unit, three tubes made of elastically deformable material, each presenting a first extremity that is integral with the central extremity of one of the three channels of said centrifugal unit with each of these tubes forming an open loop around said centrifugal unit, with the second extremity of this loop being considerably coaxial with the first one and angularly stationary, with one portion of each loop being kinematically integral with the second drive unit, with one of the tubes connected to a supply source of the liquid to be centrifuged, and with the other two used to recover the components with different densities coming from the centrifuging process. This invention also deals with the use of this device.
Such centrifugal devices are well known, such as in the area of blood centrifugation since they permit connecting the centrifuging rotor to the outside to provide a supply of liquid to be centrifuged and to remove the separated components without using an impervious seal. Indeed, from U.S. Pat. No. 3,586,413, it is known that if one has a flexible tube that forms an open loop and for which the two extremities are coaxial, with one being stationary and the other rotating at a speed of 2xcfx89 around the common axis to these two extremities, and that the loop is driven at a speed of xcfx89, the flexible tube turns around its own axis at the speed of xe2x88x92xcfx89 thus eliminating the twisting induced by the rotation of the rotor.
In the case of the centrifugation of blood, the separation enclosure must be changed to each donor or to each different patient. Taking into account the centrifugal forces required to obtain the desired separation of the components, the centrifugal rotor must be able to withstand the centrifugal forces to which it is subjected; it must be sized appropriately; it must be balanced to prevent unbalancing and it must be solidly secured to the rotation axis.
Various means have been adopted to meet these requirements: one consists of using a rotor integral with the drive system of the centrifugal device and to arrange positioning devices to receive one or several centrifugal enclosures. Such a solution is described, for instance, in U.S. Pat. No. 4,164,318.
Another solution described in U.S. Pat. No. 4,834,890 consists of arranging a rotor presenting a ring-shaped housing for the purpose of receiving a flexible pouch to be used as separation bag. Installation of the bag in the ring-shaped housing represents an extremely delicate operation. To make this operation easier, it has been proposed in U.S. Pat. No. 4,934,995 to produce the rotor in two parts in between which the housing is located to receive the flexible pouch for the liquid separation.
Another system comprising a rigid rotor for the purpose of receiving a flexible pouch for liquid separation has been proposed in U.S. Pat. No. 4,007,871. U.S. Pat. No. 4,790,807 deals with a rigid but flexible enclosure consisting of a split ring of which the two extremities are separated. To put this enclosure in place in the support rotor, the two extremities of the split ring are brought together and held in place in a rotor housed by its elasticity.
Finally, in U.S. Pat. No. 4,330,080, one has also proposed a rigid disposable rotor in the form of a disk in two parts, one comprised of two ring-shaped chambers for separating the components with different densities and channels to supply the liquid to be centrifuged and to permit evacuation of the components coming from the separation.
The drive shaft of this rotor consists of a tubular component that permits passage of the tubes for the liquid to be centrifuged and the components coming from the separation. The outside of the tube comprises a toothed annular surface for the purpose of engaging with a pinion of the drive mechanism of the device; a first disk with a convex profile is situated on one side of the toothed annular surface and serves to engage three guide pulleys with concave profiles. A second disk, situated on the other side of this toothed annular surface engages with three other guide rollers. Such a drive and guiding mechanism is extremely complex. To remove the disposable rotor, it must be possible to remove one of the rollers associated with each of the guide surfaces, so that these rollers must also be installed on mobile supports that must be locked during the centrifuging operation. As such, it is a system for which exchanging the disposable rotor represents an operation that is not easy or quick to carry out.
Consequently, it can be observed that in this case, there is no unit consisting of a rigid separation enclosure that forms a cup or bowl and its supply and evacuation tubes that permits an easy and quick exchange.
The purpose of this invention is to remedy, at least in part, the inconveniences of the aforementioned solutions.
In a first embodiment of the invention, there is provided a centrifugal device for liquids, such as blood, containing suspended particles. The device includes a first drive unit that is mounted and pivoting on a pivoting axis. A second drive unit is mounted and pivots coaxially to the first drive unit. Devices drive said first and said second drive units, with a rotational speed ratio of 2:1 between each other. A centrifugal unit for said liquid, having a center, includes at least three channels connecting the center to a peripheral separation chamber. The device further includes at least three tubes. Each tube presents a first extremity integral with a central extremity of a channel respectively of said centrifugal unit. Furthermore, each tube forms an open loop around said centrifugal unit, with a portion of each loop kinematically integral with such second drive unit. One of the tubes is connected to a supply source of said liquid to be centrifuged with at least one other tube used to recover a liquid component. The first coupling devices are integral with the first drive units, while the second coupling devices are integral with the centrifugal unit. Elastic devices are provided to exert an axial force that tends to engage, one with the other, the first and second coupling devices, so as to secure the centrifugal unit to first drive unit.
In a related embodiment of the invention, the first and second coupling devices and the elastic devices are coaxially located to the pivoting axis of the first and second drive units with the ability to be displaced along the pivoting axis against the pressure of the elastic devices.
In another related embodiment of the invention, the first drive unit includes an axial passage and the first coupling devices are a ball ring arranged circumferentially inside the axial passage of said first drive unit.
In still another related embodiment of the invention, one of said tubes linked to a collector of one of the components coming from the centrifugation process includes a proportional valve and detection devices located upstream of the tube to measure the degree of purity of a component that has to flow through said tube. The detector is connected to said proportional valve to regulate the flow in said tube on the basis of the degree of purity measured.
In yet another related embodiment of the invention, one (1) of the units assembled by the coupling devices includes an axial passage to an internal extremity to which a ball ring is coaxially installed. The other (2) of the coupling devices includes a tenon with a diameter that conforms with that of said axial passage and for which the length exceeds that of the passage. Part of the tenon protruding from said axial passage includes a ring-shaped groove sized to receive in part the ball ring and adjacent to a truncated extremity of the tenon. A tubular piston of which one extremity presents a well-formed funnel to receive such ball ring is associated with the elastic devices to press the piston axially in the direction of the extremity of said passage adjacent to said ball ring to apply such ring by exerting on it a centripetal pressure to apply balls in said ring-shaped groove. A gripping device is integral with said tubular piston to permit its displacement against said elastic devices.
In still yet another embodiment of the invention, the first and second coupling devices include a split ring-shaped elastic component coaxially arranged at an internal extremity of an axial passage of the first drive unit of which the cross-section is smaller than the diameter of the elastic component. A tubular piston of which one extremity presents a well-formed funnel receives this component, with said elastic devices pressing axially against this piston in the direction of the internal extremity of said passage to apply a split ring-shaped elastic component by tightening it radially so that its inner diameter is less than that of said passage. A gripping unit is integral with said tubular piston to displace the piston against said elastic devices.
The core of this invention is also the use of this centrifugal device as defined by claim 15.
As such, the device, according to the invention, is of the type for which the circular centrifugal unit forms a single disposable unit, integral with the tubes that supply and remove the liquids. Securing of the circular centrifugal unit to its drive unit is achieved by manual snapping into place. The securing system is not subject to the centrifugal forces since it operates axially. Once connected, there is no risk of unforeseen separation. Disconnection of the centrifugal unit only requires simple axial traction against the elastic pressure of the retaining spring. No mechanical component other than the second coupling component is located on the centrifugal unit, so that the latter is a simple part that can be manufactured cheaply. The simplicity and speed of the operations for exchanging the centrifugal unit, as well as its price, thus permit achieving a substantial gain with regard to the price of the equipment, and the cost of centrifugation. This savings is extremely important, particularly when the device according to the invention is used for collecting plasma.